when installing additional kernels for testing, make sure to increase the number of kernels the system retains, dnf is not deleting a kernel for every new one. How can I change the number of kernels retained when updating in Fedora? - #2 by augenauf describes you how to increase that number. (I would set it 5 or even higher, depending on the space available on your /boot partition).
the suggestion to hop onto a working 6.11.x one is to stick to it only until the issues are solved in 6.12.